moving_average.cc (1749B)
1 /* 2 * Copyright (c) 2018 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #include "modules/audio_processing/aec3/moving_average.h" 12 13 #include <algorithm> 14 #include <cstddef> 15 #include <functional> 16 17 #include "api/array_view.h" 18 #include "rtc_base/checks.h" 19 20 namespace webrtc { 21 namespace aec3 { 22 23 MovingAverage::MovingAverage(size_t num_elem, size_t mem_len) 24 : num_elem_(num_elem), 25 mem_len_(mem_len - 1), 26 scaling_(1.0f / static_cast<float>(mem_len)), 27 memory_(num_elem * mem_len_, 0.f), 28 mem_index_(0) { 29 RTC_DCHECK(num_elem_ > 0); 30 RTC_DCHECK(mem_len > 0); 31 } 32 33 MovingAverage::~MovingAverage() = default; 34 35 void MovingAverage::Average(ArrayView<const float> input, 36 ArrayView<float> output) { 37 RTC_DCHECK(input.size() == num_elem_); 38 RTC_DCHECK(output.size() == num_elem_); 39 40 // Sum all contributions. 41 std::copy(input.begin(), input.end(), output.begin()); 42 for (auto i = memory_.begin(); i < memory_.end(); i += num_elem_) { 43 std::transform(i, i + num_elem_, output.begin(), output.begin(), 44 std::plus<float>()); 45 } 46 47 // Divide by mem_len_. 48 for (float& o : output) { 49 o *= scaling_; 50 } 51 52 // Update memory. 53 if (mem_len_ > 0) { 54 std::copy(input.begin(), input.end(), 55 memory_.begin() + mem_index_ * num_elem_); 56 mem_index_ = (mem_index_ + 1) % mem_len_; 57 } 58 } 59 60 } // namespace aec3 61 } // namespace webrtc